Rotary kiln nose ring

ABSTRACT

A rotary kiln metallic nose ring extends about the kiln discharge end, the ring forming a series of circularly spaced ports sized and directed to pass sufficient cooling gas into the zone adjacent the kiln discharge end for flow adjacent the exposed extent of the ring as to prevent excessive heating of the ring.

United States Patent Powell 151 3,682,453 [451 Aug. 8, 1972 ROTARY KILN NOSE RING [72] Inventor: Arthur C. Powell, Redlands, Calif.

[73] Assignee: California Portland Cement Company, Los Angeles, Calif.

[22] Filed: Nov. 23, 1970 [21] Appl. N0.: 91,809

[52] US. Cl. ..263/33 R, 263/44 [51'] Int. Cl .L.....F27b 7/38 [58] Field of Search ..263/33 R, 44

[56] References Cited UNITED STATES PATENTS 3,380,407 4/1968 Nilsson ..263/33 R 2,852,242 9/1958 Simon ..263/33 R FOREIGN PATENTS OR APPLICATIONS 765,160 1/1957 Great Britain ..263/44 Primary Examiner-John J. Camby Attorney-White, Haefliger and Bachand ABSTRACT A rotary kiln metallic nose ring extends about the kiln discharge end, the ring forming a series of circularly spaced ports sized and directed to pass sufi'rcient cooling gas into the zone adjacent the kiln discharge end for flow adjacent the exposed extent of the ring as to prevent excessive heating of the ring.

10 Claims, 5 Drawing figures PAIENIEHAHHM 3,682,453

11 EN roe Her/m? 6. WE'LL ROTARY KILN NOSE RING BACKGROUND OF THE INVENTION This invention relates generally to temperature con trol of rotary kilns, and more particularly concerns the protection of kiln discharge ends from excessive heat exposure, particularly in cement clinker production applications.

The introduction of high efficiency seals between the discharge ends of rotary kilns and kiln hoods for reducing in-leakage of ambient air has resulted in substantial improvements in the efficiency of such kilns. At the same time, however, the discharge ends of such kilns became subjected to excessive heat exposure, and attempts were made to develop special internally cooled nose ring castings to protect the kiln ends.

The problem has been aggravated by the introduction of high capacity rotary kilns having relatively large diameter, and by changes in operating procedures and conditions of clinker coolers to recuperate more heat, meaning that hotter air is returned to the kiln so that higher heat values are available for combustion. While kiln operating efficiency was thereby improved, the life of the nose ring casting was substantially reduced, failure sometimes resulting within weeks or a few months after installation, and always much more frequently than kiln brick lining failure. This represents a costly operational problem, as the rotary kiln must be shut down and production halted in order to replace the nose ring casting. In addition, each time the kiln is shut down, cooling of the brick lining takes place which introduces thermal shock leading to loss of lining coating and spalling of the bricks. In this regard, experience shows that nose-ring castings which were cooled solely by heat transfer through the casting metal do not represent adequate solutions to theabove problems.

SUMMARY OF THE INVENTION It is a major object of the invention to provide satisfactory solutions to such problems through the provision of a nose ring casting characterized as passing cooling fluid into the space openly adjacent the exposed end of the ring, whereby the flow of air acts as a thermal insulator to prevent excessive heating of the ring. As will be seen, the ports may typically be elongated in the direction of annular extent of the ring; and the ring may with unusual advantage be carried by the kiln to rotate therewith, the ports being located-out of the direct path of clinker discharge from the kiln but directed to pass the cooling air into the clinker discharge as the ports are rotated beneath the lowermost extent of the kiln clinker outlet.

Additional objects and advantages of the invention include the provision of an air passage between the kiln and ring for passing cooling air to the ports; the provision of the ring in the form of an inner annulus and outer replaceable segments individually held in position; the provision of cooling ribs on the front of the ring; and the provision of kiln lining adjacent the ring, as will be described.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following description and drawings, in which:

DRAWING DESCRIPTION DETAILED DESCRIPTION In FIG. 1, cement clinker is shown slowly traveling at 10 toward the discharge end 11a of a rotary kiln 11, from which it spills at 10a toward a traveling grate not shown. One such grate is described in U.S. Pat. No.

3,091,442 to John Romig and Joseph H. Herz Hot air passing upwardly from the grate enters the kiln discharge end for combustion with fuel supplied from a burner 12 to produce intense flames at 13. The discharge end of the kiln is hooded at 44, a rather tight seal being provided between the hood and kiln to ensure against such leakage of cool air into the hood interior as would substantially reduce the temperature of hot gases flowing in the kiln to detrimentally alter clinker formation.

In accordance with the invention a protective nose ring, as-for example is indicated at 14, extends about the kiln discharge end. The ring forms a series of circularly spaced ports, as for example are indicated at 15, opening to the zone 16 adjacent the discharge end of the kiln; also, the ports are sized and directed to pass sufiicient cooling air into the zone 16 for flow adjacent the exposed extent of the ring 14 and into the kiln as to prevent excessive heating of the ring. In this regard, means is provided to supply cooling air, or other cooling gas, for flow to the ports, such means typically including a blower l6aand an annular shroud 17 extending about the kiln to form therewith an annular air flow passage 18 communicating with the ports 15.

For most advantageous cooling effect, ports 15 are typically'elongated in the direction of annular extent of ring 14. Further, the ring 14 is carried by the kiln to rotate with ports 15 remaining out of the direct path of clinker spill discharge at 10a from the kiln, but at the same time directed to pass nose ring cooling air into and through the zone 16 and the discharge 10a as the ports are-rotated beneath the lowermost extent of the kiln outlet. Accordingly, the cooling air passes in intimate cooling relation with the annular interior of the nose ringat 20, for efficient cooling of same. Cooling ribs 40 project radially at the front of the ring casting, and are circularly spaced to pass the cooling air with heat transfer thereto. FIG. 1 indicates that cooling air exits from all the ports, for flow into the kiln.

The nose ring may include an annulus 21 having a portion 21a extending at the outer side of the refactory lining or brick 22,.a portion 21b extending at the end face of that lining, and a portion 21c extending outwardly from portion2lb. Portion 210 may be retained betweenthe lining 22 and thekiln shell 23, as shown, with bosses 24 projecting into kiln lining openings 25.

replacement, as needed, without requiring shutdown of the kiln. Annulus 21 is maintained sufficiently cool, as by insulation afforded by the lining 22, and by air cooling, as not to require replacement. The segments 26 and the annulus may both consist of cast steel. As seen in FIGS. 2 and 5, each segment 26 comprises an L- shaped part 26a, and a seal part 26b to overlap the gap 31 formed between the portion 21c and the flange on part 26a that forms openings 15.

Reference to FIGS. 1 and 4 shows that the blower 16a may have a discharge duct 16b extending toward the entrance 18a of the passage 18 formed by a flared end 17a of the shroud 17, duct 16b being annularly curved at least part way about the kiln, and at the lower side thereof. This enables cooling air to circulate within passage 18 toward the nose ring, and also toward the upper side of the kiln to exit at 35, all for the purpose of keeping the kiln exit end temperature from becoming excessive.

I claim:

1. In combination with a rotary kiln having a hooded discharge end at which hot clinker is discharged to spill from the lower extent of the kiln outlet,

a. means to supply cooling gas,

b. a protective nose ring extending about the kiln discharge end and to which said cooling gas is supplied and c. said ring forming a series of circularly spaced ports opening to the zone adjacent the discharge end of the kiln and sized and directed toward said zone to pass sufficient cooling gas into said zone for flow adjacent the exposed extent of the ring and into the kiln as to prevent excessive heating of the ring,

' said ports being out of the direct path of clinker discharge from the kiln but directed to pass said cooling gas into said discharge as the ports are rotated beneath the lowermost extent of the kiln clinker outlet.

2. In combination with a rotary kiln having a hooded discharge end at which hot clinker is discharged to spill from the lower extent of the kiln outlet,

a. means to supply cooling gas,

b. a protective nose ring extending about the kiln discharge end and to which said cooling gas is supplied,

c. said ring forming a series of circularly spaced ports opening to the zone adjacent the discharge end of the kiln and sized and directed to pass sufficient cooling air into said zone for flow adjacent the exposed extent of the ring and into the kiln as to prevent excessive heating of the ring,

. said ports being elongated in the direction of annular extent of the ring, and there being cooling ribs projecting from the ring toward said zone.

3. The combination of claim 2 wherein said ring is carried b the kiln to rotate therewith and said ports are out o the direct path of clinker discharge from the 20 kiln but are directed to pass said cooling gas into said discharge as the ports are rotated beneath the lowermost extent of the kiln clinker outlet.

4. The combination of claim 3 wherein said means to supply cooling gas comprises an annular shroud extending about the kiln to form therewith an air flow passage communicating with said ports.

5. The combination of claim 2 wherein said ring includes an annulus carried by the kiln, and a circular series of segments individually connected with said annulus and forming said ports.

minal.

8. The combination of claim 5 including fasteners separately connecting the segments with said annulus.

9. The combination of claim 5 wherein said annulus and segments consist of steel castings.

10. The combination of claim 5 wherein the kiln includes refractory lining extending at the inner side of said annulus. 

1. In combination with a rotary kiln having a hooded discharge end at which hot clinker is discharged to spill from the lower extent of the kiln outlet, a. means to supply cooling gas, b. a protective nose ring extending about the kiln discharge end and to which said cooling gas is supplied and c. said ring forming a series of circularly spaced ports opening to the zone adjacent the discharge end of the kiln and sized and directed toward said zone to pass sufficient cooling gas into said zone for flow adjacent the exposed extent of the ring and into the kiln as to prevent excessive heating of the ring, said ports being out of the direct path of clinker discharge from the kiln but directed to pass said cooling gas into said discharge as the ports are rotated beneath the lowermost extent of the kiln clinker outlet.
 2. In combination with a rotary kiln having a hooded discharge end at which hot clinker is discharged to spill from the lower extent of the kiln outlet, a. means to supply cooling gas, b. a protective nose ring extending about the kiln discharge end and to which said cooling gas is supplied, c. said ring forming a series of circularly spaced ports opening to the zone adjacent the discharge end of the kiln and sized and directed to pass sufficient cooling air into said zone for flow adjacent the exposed extent of the ring and into the kiln as to prevent excessive heating of the ring, d. said ports being elongated in the direction of annular extent of the ring, and there being cooling ribs projecting from the ring toward said zone.
 3. The combination of claim 2 wherein said ring is carried by the kiln to rotate therewith and said ports are out of the direct path of clinker discharge from the kiln but are directed to pass said cooling gas into said discharge as the ports are rotated beneath the lowermost extent of the kiln clinker outlet.
 4. The combination of claim 3 wherein said means to supply cooling gas comprises an annular shroud extending about the kiln to form therewith an air flow passage communicating with said ports.
 5. The combination of claim 2 wherein said ring includes an annulus carried by the kiln, and a circular series of segments individually connected with said annulus and forming said ports.
 6. The combination of claim 1 including a burner directing to produce flame in the kiln to draw cooling air from said ports over and in cooling relation with the end of the kiln.
 7. The combination of claim 4 wherein said shroud extends from the nose ring along the kiln to a terminal which is annularly flared away from the kiln, and said means to supply cooling gas includes a blower having a discharge proximate the entrance to said flared terminal.
 8. The combination of claim 5 including fasteners separately connecting the segments with said annulus.
 9. The combination of claim 5 wherein said annulus and segments consist of steel castings.
 10. The combination of claim 5 wherein the kiln includes refractory lining extending at the inner side of said annulus. 